Fiberglass insulation products generally consist of glass fibers bonded together by a cross-linked polymeric binder. An aqueous polymer binder is sprayed onto matted glass fibers soon after they have been formed, and while they are still hot. The polymer binder tends to accumulate at the junctions where fibers cross each other, to hold the fibers together at these points. The heat from the fibers causes most of the water in the binder to vaporize.
The polymeric binder has been a phenol-formaldehyde polymer. More recently formaldehyde-free polymer systems have been used to avoid formaldehyde emissions. The formaldehyde-free polymer system consists of 1) a polymer of a polycarboxyl, polyacid, polyacrylic, or anhydride; 2) an active hydrogen compound (hydroxyl or polyol group) such as trihydric alcohol (U.S. Pat. Nos. 5,763,524; 5,318,990), triethanolamine (U.S. Pat. No. 6,331,350; EP 0990728), beta-hydroxy alkyl amides (U.S. Pat. No. 5,340,868; or hydroxy alkyl urea (U.S. Pat. Nos. 5,840,822; 6,140,388); and 3) a catalyst or accelerator such as a phosphorous-containing compound (U.S. Pat. No. 6,136,916) or a fluoroborate compound (U.S. Pat. No. 5,977,232). The catalyst functions to decrease the cure time, to increase the cross-linking density, to reduce the cure time and/or to decrease the water sensitivity of the binder.
One problem with current catalysts is that they produce films that can discolor. Also the films may release phosphorous-containing vapors.
There is a need for a fiberglass binder system having a catalyst other than the phosphorous or fluoroborate catalysts currently used.
Surprisingly it has been found that Lewis acids, Lewis bases, and free-radical generators are effective catalysts for crosslinking polymeric binders for fiberglass non-wovens. The use of these catalysts produces a strong, yet flexible and clear, fiberglass insulation binder system.